Dry cell



June 23, 1953 Filed June 21, 1949 i 1 i ll} I Zvge/cim? (9%3272444" l/gjimp amv PZZMZ 4 Patented June 23, 1953 UNITED STATES PATENT OFFICE DRY CELL Arthur W. Simpson, Freeport, IlL, assignor, by

mesne assignments, to Burgess Battery Company, Freeport, 111., a corporation of Delaware Application June 21, 1949, Serial No. 100,420

7 Claims. (Cl. 136133) This invention relates to dry cells and particularly to improvements in the type of dry cell such as is used in flashlights which has an opentop metal cup which serves as the negative electrode. The invention is directed to the provision of an improved seal closure for such a dry cell.

It is the principal object of the invention to provide a dry cell in which the top edge of the cup is turned inwardly to form an in-turned peripheral flange and a preformed, stiff, non-conductive, wafer-shaped closure member is provided and arranged with its outer peripheral edge in sealing pressure engagement with the edge of the flange of the cup.

Closures in the form of preformed disks or wafers have been used in the past, but in accordance with the present invention it has been found that a stronger and tighter seal is formed and at the same time a thinner Wafer may be used when the edge of the metal cup is turned inwardly and caused to engage with strong pressure the outer edge of the wafer.

Objects and advantages in addition to those which have been mentioned above will become apparent as the following description progresses. in the accompanying drawing,

Figs. 1 and 3 are plan views, partly in section, of different embodiments of the improved dry cell of the present invention, and

Figs. 2 and e are perspective views of the preformed closure members employed in the dry cells of Figs. 1 and 3 respectively.

Referring to Figs. 1 and 2, the dry cell thereof is of the cylindrical shape usually used in flashlights. It has an open-top metal cup is which serves as the negative electrode, and may be composed of a suitable metal such as zinc. The top edge of the cup is turned inwardly to form the in-turned flange 12, which is continuous around the periphery of the cup and extends inwardly a substantial distance for a reason which will be explained hereinafter. Upon the. interior surface of the side wall of the cup is a and the seal of the present invention is especially advantageous with a layer of this character.

In one method of cell construction the layer oi 2 starch Hi is applied in the form of a viscous aqueous suspension of the starch by a centrifugal operation which distributes the suspension over the side wall of the metal cup to the top edge. thereof, after which it dries in position.

Interiorly of the layer [4 is a mass it of depolarizing mix which may be of a suitable composition, such as manganese dioxide and carbon. Themass i5 and the bibulous layer l4 are moistened with the electrolyte, which may be of any suitable composition, such as an aqueous solution of ammonium chloride and zinc chloride. Embedded centrally Within the mix 16 is the upright positive electrode l8, which may be composed of a suitable substance such as carbon. The electrode 18 projects above the top of the mix is and a conductive metal terminal cap 20, which may be composed of brass or other suitable metal, fits tightly upon the upper end thereof. In accordance with the present invention, a stifi wafer-shaped, non-conductive, electrolyteresistant closure member 22 is provided for the open top of the cup at. In the case of the cylindrical cell illustrated, the closure member 22 is in the form of a washer but the cell may be of other than cylindrical shape. The washer 22 fits over the terminal 2?; and makes edge-to-edge engagement with the flange l2 and is spaced above the top of the mix iii. The washer 22 has a central opening 24 of a size such that it fits tightly upon the terminal 29 and electrode is. The Washer 22 has a thickness substantially greater than that of the metal cup it and preferably several times the thickness of said cup. The size of the washer is such that its outer edge makes tight pressure contact with the edge of the flange E2. The washer 22 is composed of a substance having sufficient stifiness that it is substantially rigid against bending. It may have elastic compressibility such that the diameter of the opening it is substantially equal to or slightly less than that of the positive electrode I 8 and it may be pushed down over the metal terminal 28 and partly below said terminal, in which case it expands and makes sealing pressure contact with the electrode i8, as shown in Fig. 1. -In the same manner, the outer diameter may be greater than the inner diameter of the flange lZin whichcasethe edge of the flange.

and central terminal.

makes a circumferential indentation in the edge of the washer 22 and the two edges are in sealing pressure contact with each other. Rubber having a durometer scale of hardness of 80 to 100 is suitable for the purpose. In a practical method of inserting washer 22, it is machinepressed down over the terminal 20 and the flange i2 is at the same time turned inwardly in such manner that the washer and flange move together to their final positions. In this manner a pressure toggle action occurs at the engaging edges of the washer and flange in which the flange makes a single clean-cut indentation in the washer. The flange i2 is caused to extend inwardly a substantial distance and the outer diameter of the washer is substantially less than the inside diameter of the cup below the flange. and contact between the flange and the washer 22 is substantially confined to the edges of the latter parts. A jacket 25 of suitable non-conductive material such as cardboard encloses the exterior side wall of the cup It in the manner usual with cylindrical cells.

The materials of which the sealing member 22 may be composed are rubber, either natural or synthetic, polyethylene, polyvinyl chloride, the copolymer of vinyl chloride and vinyl acetate, polyvinylidene chloride, the copolymer of v'inylchloride and vinylidene chloride, the organo-silicon oxide polymer (Silastic) and the like. Some of the substances, such as polyethylene and those containing vinyl chloride, are thermoplastic and, if desired, after the washer is in place, heat may be applied locally to the edge thereof at the junction with flange if, as by a local flaming operation, sufficient to soften the substance of the washer and cause it to flow slightly and form a heat-sealed joint with the flange l2.v The same may be done at the junction of the washer with the terminal 2E3 if desired.

The closure of the present invention has the advantage that it makes a tight sealing joint with the electrode. 18 and terminal 20 and also with the flange E2 of the metal cup. The narrow edge-to-edge contact between the closure 22 and the flange l2 makes it possible to obtain high pressure at the line of contact with resulting great tightness of the seal. The closure is, in addition, very strong because it is firmly held at its inner and outer edges. The turning-in of ,member has a peripheral groove in its outer edge. The same numerals will be used to designate parts corresponding to those of the cell of Figs. 1 and 2. The closure washer 26 has a preformed circumferential groove 28 in its outer edge and the flange l2 and the layer l l'are received'in the groove. In this construction, the arrangement is such that the edge of the flange I2 makes firm pressure engagement with the base of the groove. As in the structure of Figs. 1 and 2, the flange l2 of the cup [0- extends inwardly a substantial distance and contact be-' tween the flange and washer 26 is confined to the groove and the flange, and the outer edge of the washer is spaced from the interior surface of thebody of the cup below the flange.

While but two embodiments of the invention have been described and illustrated, the invention is not limited thereto but only in accordance with the scope of the appended claims. For example, while cells have been described which are cylindrical in shape, the invention is not limited to such shape, and the cup may be of rectangular or other angular shape, in which case the closure member is in the form of a wafer suitably shaped to conform to the shape of the cup.

What is claimed is:

1. In a dry cell, an open-top metal cup having its top edge-portion turned inwardly to form a narrow in-tulned peripheral flange having an in wardly-facing edge, a terminal in said cup and spaced therefrom, a seal closure for said open top com rising a preformed stiff non-conductive the top edge of the cup Ill has a reenforcing effeet upon the strength of the cell at this point, and the tight pressure contact between the flange and the washer has an additional reen-forcing effect upon the strength of the cell. At the same time, the washer 22 may be thinner than has been required heretofore in preformed closures which are mechanically joined to the metal cup In addition, the closure of the present invention is especially advantageous with a cell in which the bibulous layer Hi extends to the top of the metal cup as shown. The edge-to-edge contact between the cup and washer forms a positive seal, which would not be possible if the top edge of the cup were not turned in. In such case, the closure would make contact with the bibulous layer it upon the interior surface of the cup. A strong mechanical joint cannot be made with the bibulous layer and any such joint would not form a satisfactory seal, but would permit the escape of cell liquid.

In the embodiment illustrated in Figs. 3 and '4 the construction is the same as has been described with the exeception that the closure flat wafer tightly impaled upon said terminal and extending from said terminal over said open top of said cup and having an outwardly facing edge brought into edge-to-edge sealing pressure en-= gagenient with said inwardly facing edge of said flange by a toggle motion of said flange and said wafer, said terminal being exposed through said wafer.

2. The construction as claimed in claim 1 in which the width of the outwardly facing edge of the seal wafer is substantially greater than that of the inwardly facing edge of the in-turned flange of the cup.

3. The construction as claimed in claim 1 in which the wafer is of thermoplastic composition and is heat-sealed to the flange of the cup.

4. The construction as claimed in claim 1 in which the seal wafer is composed of stiff, elastic, compressible, non-conductive material and the inwardly facing edge of the in-turned flange of the cup makes a peripheral indentation in the outwardly facing edge of the wafer by pressure engagement therewith.

5. In a dry cell, an open-top metal cup having its top edge portion turned inwardly to form a narrow in-turned peripheral flange having an inwardly facing edge, a terminal in said cup and spaced therefrom, a seal closure for open top comprising a preformed stiff non-conductive flat wafer tightly impaled upon said ter minal and extending from said terminal over said open top of said cup and having an out wardly facing edge, said last mentioned edge having a peripheral groove therein, the inwardly facing edge of said flange being brought into sealing pressure engagement with the base of said groove by a toggle motion of said flange and, said wafer, said terminal being exposed through said wafer.

6. A drycell as claimed in claim 5 in which contact between the sealing wafer and the metal cup is confined to the groove of the wafer and the in-turned flange of the cup.

7. In a dry cell, an open-top metal cup having its top edge-portion turned inwardly to form a narrow in-turned peripheral flange having an inwardly facing edge, an upright electrode in said cup and spaced therefrom, a bibulous non-conductive layer lining the interior surface of the side walls of said cup and extending to the top edge of said cup, a mass of mix between said bibulous layer and said upright electrode, a seal closure for said open top of said cup comprising a preformed stiff non-conductive flat wafer tightly impaled upon said upright electrode and extending from said electrode over said open top of said cup and having an outwardly facing edge brought into edge-to-edge sealing pressure engagement with said inwardly facing edge of said flange by a toggle motion of said flange and said wafer, said electrode being exposed through said wafer.

ARTHUR W. SIMPSON.

References Cited in the file of this patent UNITED STATES PATENTS Number 

